Types of Tile and Stone Compatible with HeatTech Floor Heating Systems
The importance of R-value
When the type of flooring has been decided on, it is important to consider its compatibility with an electric in floor heating system. A general rule of thumb to use is to ensure that the combined R value of the flooring above the heating cable or mat is at or below 1.0
Thickness of the flooring may vary greatly – anywhere from 1/4” to 3/4” or more and should be accounted for when determining the R value.
This data can usually be obtained from the product manufacturer, distributor or the architect.
Compatible flooring types
In order for the heating system to efficiently transfer the heat to the surface of the floor, the material should conduct heat well, be structurally stable, water resistant and be of adequate thickness. Common choices include ceramic (including porcelain), natural stone and glass tiles.
Ceramic & Porcelain Tile
A most widely used and practical choice of flooring for a radiant in-floor heating system. Porcelain tiles are denser and are more impervious to water and therefore are a better choice for areas exposed to a lot of moisture, such as showers and saunas. When buying porcelain tiles, organizations such as PTCA (Porcelain Tile Certification Agency) may be a useful source for verifying tile manufacturer claims about water impermeability. Ceramic tiles are a good choice for kitchens, bathrooms, lobbies and other areas with low or no moisture.
Natural Stone Tile
The most common types of natural stone tile flooring are Granite, Marble, Slate, Travertine and Limestone – all with an abundance of finishes, textures and characteristics. According to various scientific sources, their density is about the same: 2.4-2.7 g/cm3 (grams per cubic centimeter), however their hardness on MOHS scale varies greatly, from as high as 6.5 for granite and only 3.0 for marble.
While all of the above can be successfully used with an in-floor heating system, granite would be the optimal flooring choice, both due to durability (resistance to cracking, scratching and staining) and good heat conductivity.
Marble is a softer rock and has relatively high water permeability, and therefore is not recommended for areas exposed to moisture – kitchens, bathrooms, showers, etc. Similarly, slate and limestone score only 3.0-4.0 on hardness scale and are prone to staining and scratching and are only suitable for dry, low traffic areas.
Tile Adhesive (Thinset)
Presently, there are two main types of thinset on the market – modified and un-modified (a.k.a. dry-set). Modified thin-set usually contains latex, acrylic, EVA, PVA or other additive to enhance its properties such as elasticity, moisture impermeability, freeze resistance and others. According to TCNA (Tile Council of North America), the amount of different polymer additives produced for thinset exceeds 10,000.
Un-modified thinset is often called dry-set and does not contain any additives.
For wet areas such as showers, bathrooms, kitchens and alike, modified (waterproof, latex or acrylic) thin-set is a must, to protect the electric under floor heating system from contact with water. Dry-set is generally not recommended for use with HeatTech system since it lacks the necessary stability, crack and moisture resistance required. Always check with thinset manufacturer to ensure compatibility of their product with an electric in-floor radiant heating system.
Mats or Cable
Wood Floors - includes hardwood and softwood.